1. Technical Field
The present invention relates to a piezoelectric element, a liquid ejecting head, and a sensor.
2. Related Art
As a piezoelectric element, there is a piezoelectric element configured by sandwiching a piezoelectric layer including a piezoelectric material showing an electromechanical conversion function, for example, a crystallized piezoelectric material with two electrodes. Such a piezoelectric element is installed in a liquid ejecting head, for example, as an actuator for a flexural vibration mode. As a typical example of a liquid ejecting head, for example, there is an ink jet type recording head in which a part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is configured with a vibration plate, an ink in the pressure generating chamber is pressurized by deforming the vibration plate by using the piezoelectric element, and the ink is discharged from the nozzle opening as ink droplets.
Presently, lead zirconate titanate (PZT) in which lead is used as a main component, is generally used for a piezoelectric material used as a piezoelectric layer configuring the piezoelectric element (for example, refer to JP-A-2001-223404), however, there is a need to develop a lead-free based piezoelectric material which does not include lead from the viewpoint of environmental problems. As a lead-free based piezoelectric material, for example, there is an oxide in which bismuth ferrate or barium titanate is solutionized (for example, refer to JP-A-2009-252789). Furthermore, in order to enhance the piezoelectric characteristics such as a displacement amount, it is possible to use a piezoelectric material in which an alkali metal is introduced into bismuth ferrate, for example, an oxide in which bismuth ferrate, bismuth potassium titanate, and bismuth manganite are solutionized (for example, refer to JP-A-2011-066382), sodium potassium niobate, bismuth sodium titanate, and the like.
However, currently, the large displacement amount enough to surpass that of lead zirconate titanate has not been obtained by such a piezoelectric material yet. In addition to that, in the piezoelectric material including an alkali metal such as sodium potassium niobate or bismuth sodium titanate, there is also a possibility in which changes over time such as moisture absorption of an unreacted alkali metal occur.
Meanwhile, such a problem is not limited to the piezoelectric element which is installed in an ink jet type recording head and similarly exists in piezoelectric element which is installed in other liquid ejecting heads which discharge liquid droplets other than an ink and a piezoelectric element which is installed in a sensor.
An advantage of some aspects of the invention is to provide a piezoelectric element which is configured with a lead-free based piezoelectric material which does not include an alkali metal and in which a displacement amount is enhanced, a liquid ejecting head provided with the piezoelectric element, and a sensor.